The present invention concerns a method of manufacturing a metallic-composite joint. More particularly, but not exclusively, this invention concerns a method of manufacturing a metallic-composite joint where the metallic-composite joint comprises a metallic component, the metallic component and a metallic fastener, the metallic fastener having ahead portion for attaching to the metallic component and a tail portion for attaching to a composite component.
The invention also concerns a metallic-composite joint, a structure, an aircraft structure, an aircraft, a method of manufacturing a fastener assembly, a fastener assembly and a metallic fastener.
There are various methods of attaching a metallic component to a composite component to form a metallic-composite joint.
One method involves making the surface of the metallic component liquid by heating it to a very high temperature. A metallic spike is then formed extending away from the surface by forming a “proggle”. In other words, an implement is contacted with the liquid surface and pulled up away from the surface (“proggling”) to form a metallic spike. This spike is made of the same metallic material as the metallic component. The composite component is then attached to the metallic spike (known as a hyper pin) by either laying up fibre layers so that adjacent fibres lie either side of the spike or by shaking the fibre layers onto the spike. The fibre layers are then cured so that the cured composite component is attached to the metallic spike. This process can be time-consuming and expensive.
Another method uses ALM (Additive Layer Manufacturing) to form the metallic spike (hyper pin) on the surface of the metallic component. The composite component can then be attached to the spike, using the two ways described for the earlier method. ALM is also a time-consuming and expensive process. In addition, ALM machines tend to be of a limited size and so can generally only be used to produce smaller pins and so there is a limit to its applicability, especially with large components,
For both of these methods, the metallic spike has to be the same material as the metallic component. For example, in aerospace applications, it is often desirable to use an aluminium alloy as the material for the metallic component. However, this then means that, using the methods described earlier, the metallic spike is also made of the aluminium alloy. This can cause problems as aluminium alloy is not readily compatible with composite materials. Hence, so that aluminium alloy and composite materials are prevented from being adjacent to each other, a titanium alloy is used instead for the metallic component. Titanium alloy is more compatible with composite materials so this problem is overcome. However, it is more expensive than aluminium alloy and so is disadvantageous for that reason.
The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved method of manufacturing a metallic-composite joint.